<!DOCTYPE html>
<html lang="en">
<head>
  <meta charset="UTF-8">
  <meta http-equiv="X-UA-Compatible" content="IE=edge">
  <meta name="viewport" content="width=device-width, initial-scale=1.0">
  <title>Document</title>
  <link href="https://cdn.jsdelivr.net/npm/bootstrap@3.3.7/dist/css/bootstrap.min.css" rel="stylesheet">
</head>
<body>
  <div class="container">
    <h2 class="page-header">按钮</h2>

    <button>我是一个小按钮</button>
    <button class="btn">按钮</button>
    <button class="btn btn-default">按钮</button>
    <button class="btn btn-primary">按钮</button>
    <button class="btn btn-info">按钮</button>
    <button class="btn btn-success">按钮</button>
    <button class="btn btn-warning">按钮</button>
    <button class="btn btn-danger">按钮</button>
    <hr>
    <button class="btn btn-primary btn-lg">按钮</button>
    <button class="btn btn-primary btn-md">按钮</button>
    <button class="btn btn-primary btn-sm">按钮</button>
    <button class="btn btn-primary btn-xs">按钮</button>

  </div>
</body>
</html>